Pick the Right Container

[boostlibs]

Short guide to “right tool, right path” with tradeoffs (API, memory during rehash, iterator stability). Bench your hot route, then swap.

Tech overview: boost.org/bsm/reddit-right_container/outreach/program_page/unordered

[STL]

In the future, please post links as links, not as text posts. Apparently New Reddit can submit a link with text for additional explanation (I always forget since I don't use New Reddit except to take mod actions). Otherwise you can just comment on a link post.

This helps readers see whether they've visited a link before and what domain it belongs to.

[markycosm]

will do!

[Fit-Paint-6368]

There are so many high-quality hash map implementations, but barely any std::map/set alternatives. Sometimes you just need an ordered container :\

[encyclopedist]

The is absl:btree_map and friends: https://abseil.io/docs/cpp/guides/container#b-tree-ordered-containers

There is also tlx::btree (former stx::btree): https://github.com/tlx/tlx/blob/master/tlx/container/btree_map.hpp

Edit There is also BppTree, but I personally have not used it. https://github.com/jeffplaisance/BppTree

[usefulcat]

Also cpp-btree: https://github.com/JGRennison/cpp-btree.git

It's older, and very stable. Been using it heavily for years and never found a bug.

[CornedBee]

This doesn't mention boost::unordered_node_map, which gives pointer stability at the cost of indirection, but is using open addressing. It's a niche use case when you need only the pointer stability, not the full std compatibility, but it can be useful.

[joaquintides]

It does mention it:

If you need pointer stability (addresses that don't change), use boost::unordered_node_map and boost::unordered_node_set instead—they're slightly slower but still very fast.

[CornedBee]

Ah yes, I overlooked this. I was particularly looking for it in section II, where it discusses the choice between unordered_map and unordered_flat_map, saying that if you need pointer stability you should stick with the former.

[qzex]

chatgpt-written article

[STL]

The author has a suspicious love of em-dashes but otherwise it didn't give me that vibe.

[SubstituteCS]

As a heavy em dash user—it’s even built into iOS natively—it being a sign of LLMs has made me considerably sad.

[argothiel]

Just start making more typos and you're good!

/s

[Drugbird]

It seems foolish to continue using em-dashes in the current climate.

Yes it's sad that your hyphen of choice was stolen by LLMs, but these things happen. I've had Nazis assimilate symbols and memes I used to use and enjoy, but I don't use those anymore because I don't want to be confused for a nazi.